1. Field of Invention
The present invention relates generally to methods of controlling clutches of vehicles and, more particularly, to a method of controlling a clutch in the launch conditions of an AMT or DCT vehicle generated when a driver manipulates an accelerator pedal during creep driving.
2. Description of Related Art
In conventional Automated Manual Transmissions (AMTs), Dual Clutch Transmissions (DCTs), etc. which use dry clutches, creep driving, which is generated in an existing automatic-transmission vehicle provided with a torque converter, is created by controlling a clutch. The clutch is controlled such that even when a driver does not step on an accelerator pedal, the vehicle moves slowly.
When a driver steps on an accelerator pedal during the creep driving, the driving of the vehicle is controlled depending on the extent to which the accelerator pedal is pushed. The control operation conducted at this time refers to launch control.
FIG. 1 is a flowchart of a conventional method of controlling the torque of a clutch when the control of a vehicle is converted into the launch control during the creep driving. FIG. 2 is a graph of variations in a clutch control torque, the RPM of an engine, and the RPM of an input shaft of a transmission in the conventional control method.
Referring to FIG. 1, a controller calculates a creep torque which is a clutch control torque during creep control and controls a clutch depending on the creep torque. When the vehicle is in a creep driving state, if a driver manipulates an accelerator pedal so that an APS is actuated and launch control is required, the controller calculates both a creep torque which is a clutch control torque during the creep driving and a launch torque which is a clutch control torque required for the launch control resulting from the manipulating of the accelerator pedal, and then selects a higher value of them as the clutch control torque to control the clutch.
According to the above-mentioned conventional control method, when the driver manipulates the accelerator pedal during the creep control, the creep control is converted into launch control. At this time, the clutch control torque is rapidly increased to a degree that is much higher than the clutch control torque in the creep driving. As shown in FIG. 2, this causes rotational vibration of the input shaft of the transmission, thus resulting in jerking of the vehicle.
The jerking of the vehicle, which is caused when the accelerator pedal is pushed during the creep driving, causes a rough ride of the vehicle, thus deteriorating the merchantability of the vehicle.
The information disclosed in this Background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.